Author Topic: Spray foam roof insulation (Read 4709 times)

jdtuttle · « **on:** February 13, 2008, 07:47:46 AM »

I'm planning a timber frame addition to my shop and was wondering if anyone has done this before. I will have 4 bents 8' OC with purlins 4' OC. I would then install 2x6 T&G below the purlins. The insulation would then be sprayed from above & then install 2x6 T&G on top. Tar paper & metal roofing to finish. Has anyone done this before? Is there a difference in cost vs. foam panels?
jim

Don_Papenburg · « **Reply #1 on:** February 13, 2008, 09:40:30 PM »

I had icynene sprayed in my attic. If you can do foam panels (like blueboard or foamular pink ) it would be a lot cheaper. another option ro look into would be SIPs panels

StorminN · « **Reply #2 on:** February 15, 2008, 10:44:20 PM »

I think the cheapest foam is the EPS foam (normal white expanded polystyrene) that they use in the SIPs panels. Out here you can buy it direct from Insulfoam and save a ton. It's much cheaper than the EPU (expanded polyurethane) that the blue or pink board is made of, which is cheaper than the polyisocyanate spray-foam stuff. Now I'm told the EPS does not have as high an R-value per inch as the EPU, so it will take more inches of EPS to do the same job, but I believe if you have the room, the EPS is still cheaper for the same R-value... I haven't looked into it that much.

I don't have any firm figures on this stuff, but I'll be researching this same thing this spring / summer, so I will find out...

-Norm.

jdtuttle · « **Reply #3 on:** February 16, 2008, 07:16:19 AM »

I think your right Norm. I built a timberframe addition on my house 6 years agou & used Murus SIP's for the skin. It's the warmest room in the house. For the shop I'll keep an eye out for some used commercial roof panels. There listed on ebay all the time.
Thanks,
jim

M Williams · « **Reply #4 on:** February 16, 2008, 08:58:04 AM »

I cant remember for sure , but I think the fomofoam? company gives the specs on how many board ft of insulation that their product makes for a given container size and the cost. I guess you could compare cost to buying premade panels.

shopteacher · « **Reply #5 on:** February 17, 2008, 09:59:01 AM »

Go around and collect all them packing peanuts out of the dumpsters and get them two brothers a working up on the roof.

tim1234 · « **Reply #6 on:** February 17, 2008, 10:25:52 AM »

Quote from: jdtuttle on February 13, 2008, 07:47:46 AM

I'm planning a timber frame addition to my shop and was wondering if anyone has done this before.

Check out this thread in Timber Framing. A Very similar discussion going on the last few weeks.

http://www.forestryforum.com/board/index.php/topic,29403.0.html

Tim

jdtuttle · « **Reply #7 on:** February 17, 2008, 02:48:45 PM »

Thanks Shopteacher,
I think I'll send them two brothers out to the dumpsters to pick-up the peanuts

olyman · « **Reply #8 on:** February 17, 2008, 04:24:50 PM »

Quote from: M Williams on February 16, 2008, 08:58:04 AM

I cant remember for sure , but I think the fomofoam? company gives the specs on how many board ft of insulation that their product makes for a given container size and the cost. I guess you could compare cost to buying premade panels.

i checked this out--as want to do a house i moved in the country this way--to seal it up tight enough to heat it with a matchstick!!!! thanks

tim1234 · « **Reply #9 on:** February 17, 2008, 04:58:14 PM »

Quote from: olyman on February 17, 2008, 04:24:50 PM

i checked this out--as want to do a house i moved in the country this way--to seal it up tight enough to heat it with a matchstick!!!! thanks

I checked on buying the FrothPaks years ago and found it was cheaper to contract it out rather than buy a bunch of dual 20 lb bbq propane tank size kits (good for 600 board feet if I remember right). The pro's showed up with a truck and 4 - 55 gal drums of material ( 2 part a and 2 part b). It still took 2 days to spray the whole house. Just the roof and the bond between the foundation block and the rim joist.

The one thing you have to remember when using the portable tank style foam kits is the part a and part b are mixed in the nozzle. That means you can't stop spraying for more than a minute (plus or minus) or the foam hardens in the tip. The kits come with a bunch of different fan or stream tips but you can really rip through them if you have to stop to reposition a lot. The hoses and gun are ok at least for a lot longer than the tips. Then my local trash collectors would not take the spent tanks. I think they thought they were propane tanks and kept leaving them a the curb. So you have to find a place to dispose of the tanks.

I have used the kits for a smaller job and they work reasonably well. You just need to be aware of the limitations.

Tim

olyman · « **Reply #10 on:** February 18, 2008, 01:46:17 PM »

i hear ya. except that i am going to have to do what i want to do in stages. so cant get the large contractor to do it. can take my time also. and disposing of tanks is no problem for me.......

ScottCC · « **Reply #11 on:** December 30, 2016, 11:26:42 PM »

I am planning a similar situation for my spec house and hear is how I plan to beat the money. I will install layers of foam board, leaving gaps next to purlins. Then finishing with spray in intentional gaps and over entire face of foam boards. All the seal 65 percent of the money or better, same r value.

hedgerow · « **Reply #12 on:** January 01, 2017, 10:02:23 PM »

Back in 03 we remodeled a three story farm house and looked at a lot of ways to insulate the house. Back then in this area their wasn't a lot of spray foam going on. I felt this was the way I wanted to go. I looked at the tanks that didn't seem to pan out. I even looked into buying the equipment and then selling it when we were done. We also were thinking of installing a Garn boiler and would insulate it and the feed lines. You may look at roofing company's as they spray foam a lot and may catch them when the weather won't let them do roofs. That is what we did and found a guy that did roofs and needed a new AC, furnace for his house. He did a lot of foam for me and I installed a new AC, furnace in his house. I had to do some waiting and had everything ready so when they showed up they rolled but it saved me a ton of money and we love the spray foam. I wouldn't ever insulate without it.

woodshax · « **Reply #13 on:** January 02, 2017, 12:55:33 PM »

My 2 cents.....I used to own a spray foam business (sold out to my partner in 2013)....love the product...hate the business model. I would caution against a do it your self spray foam kit....the 600 Bd ft....is best case with an experienced sprayer and properly spraying is an art form that takes a while to master... you would likely end up sraying yourself and loved ones more than the roof.....Most of your heat loss is the roof and that has the most bang for your buck (think of all the holes with windows and doors and you will see why)...... and R Value is not straight forward as six inches of open cell foam while having about an R-20 is the same as an R-30+ of batting or blown in because of the continuous seal. Closed cell is more expensive but a much better deal as 2.5 inches is more than enough (anything over that there is very little gain in efficiency ...maybe 1% per inch)....also you may want to stay away from not covering the application with a 30 minute fire barrier (sheetrock or thick paneling) as open cell has a relatively low combustion temp so the fire code says that if exposed in an attic it needs a ignition barrier sprayed on for open cell....most closed cell have that 5 minute rating.....if there is storage or people who could have access to the area is is supposed to have a 30 minute fire rating which is a very thick (like 12 mils) coating of the fire retardant (expensive) most home owners opt out....but if there is a fire....insurance companies are always looking for a reason not to pay off....this is an easy one. I have sprayed most types of foam and some are better than others...the A side is isocyanate and everyone uses the exact same stuff....the B side is the resin and that is where the difference comes in ...in R value, yield etc

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